Anthropic Claude Opus 4.5: LLM Security & Jailbreak Resistance
As of 2026-07-04, Anthropic Claude Opus 4.5 has an attack success rate (ASR) of 3.4% on Guardion's LLM Vulnerability benchmark — ranking #1 of 93 models. It is highly resistant to jailbreaks and adversarial prompts.
Attack Success Rate (ASR) is the share of adversarial prompts that elicit harmful output across zero-shot, TAP, and Crescendo attacks (HarmBench framework). Lower is safer. "Est." models are calibrated from public safety evaluations pending a Guardion benchmark run.
How Claude Opus 4.5 compares
Frequently asked questions
How secure is Anthropic Claude Opus 4.5 against jailbreaks?
Anthropic Claude Opus 4.5 is highly resistant to jailbreaks and adversarial prompts. On Guardion's LLM Vulnerability benchmark it records a 3.4% attack success rate (96.6% robustness), ranking #1 of 93 models (estimated from public safety evaluations).
What is Claude Opus 4.5's attack success rate (ASR)?
Claude Opus 4.5's overall ASR is 3.4% — the share of adversarial prompts that elicit harmful output across zero-shot, TAP, and Crescendo attacks. Lower is safer.
Is Claude Opus 4.5 more secure than Claude Sonnet 4.5?
Claude Opus 4.5 is more robust: 3.4% ASR vs Claude Sonnet 4.5's 4.2%. See the full head-to-head comparison for the per-attack breakdown.
How can I make Claude Opus 4.5 safer to deploy?
Even robust models are bypassed under sustained attack. An inline runtime guardrail that classifies prompts and responses — like Guardion's prompt-defense models — blocks jailbreaks and prompt injection before they reach Claude Opus 4.5.
Harden Claude Opus 4.5 in production
Guardion's runtime guardrails block jailbreaks and prompt injection before they reach any model — with sub-130ms policy decisions.
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